587 may be the default SMTP port recommended with STARTTLS. Pretty much all email assistance suppliers support it. As long as there aren't any troubles, the receiver’s mail server will use the protocols POP3 or IMAP to retrieve the email and deliver the message to its meant receiver. Like https://www.upwork.com/services/product/development-it-migration-to-magento-2-nodejs-in-new-vps-server-aws-linode-digitalocean-1445680653983371264?ref=project_share&tier=0